funding for this program was provided by... human beings are all one species. we are all equally capable of language, creativity,

and thought. the differences among us lie in our cultures, our beliefs, how we organize our societies and how we make our living. humans have populated every environment on earth. we live on the frozen tundra and in the searing deserts. we live in thriving cities of millions and in isolated camps of a few dozen. some societies seem simple because they are small and their members are self-sufficient and use simple tools. others seem complex because they have large populations and people depend on each other for food and goods and use sophisticated technology.

in between, there is a range that fills the spectrum. all of these differences are cultural, learned behavior, the result of a complex interaction between our inventiveness and our natural environments. as we search for new horizons, our inventiveness thrusts us across the boundaries of space, into new worlds. this new view of earth dispels an ancient myopia -- the artificial boundaries of our states and the politics that often divide us. here is a vision of one planet and one family of humankind. but the view from earth reminds us of a common human dilemma,

the rise and fall of our many ways of life. here, among the ruins of ancient civilizations, archaeologists are retracing the steps in a long and shared human odyssey. across two worlds, the old and the new, they are discovering the independent spark of the human genius, the many times and places that we have created grand civilizations.

ancient egypt. as early as the 18th century, scholars came here to marvel at and study the great relics of the ancient sun kings. laboring among the pyramids and temples of this old-world civilization, early archaeologists speculated that complex civilizations were created in the near east to spread far and wide. they thought the greek city states, the roman empire, and all the civilizations that followed were the inheritors of a single act of creation. but discoveries in the new world would provide a stunning challenge to this myopic vision of human history. in 1839, in the jungles of mesoamerica,

explorers john lloyd stephens and frederick catherwood encountered the realms of the ancient maya. europeans were amazed by catherwood's written descriptions of ancient maya cities. architecture, sculpture and painting -- all the arts that embellish life had flourished in this overgrown forest. who built this city ? in the ruined cities of egypt, the stranger knows the story of the people whose vestiges are around him. america, say the historians, was peopled by savages. but savages never reared these structures, never carved these stones. we asked the indians who made them ? and their answer was "quien sabe ?" -- who knows ? during the next century, other explorers revealed the amazing variety of new-world civilizations. a great city, teotihuacan, dominated the basin of mexico.

atop a hill in the valley of oaxaca, sits monte alban, the royal center of a mighty kingdom. and in the forests and jungles of guatemala, maya city states once reigned over thousands of square miles. this is mesoamerica. at about a.d. 700, three great civilizations had emerged here. the realms of the maya. the power of the great city of teotihuacan. the zapotec kingdom of monte alban. for many scholars the differences between new and old-world civilizations suggested an independent course of history -- that each evolved on its own. this led to another and deeper insight -- beneath these differences

may lie a grand and universal similarity, a parallel course of human evolution throughout the world. we now know that all humans once lived nomadic lives. we gathered wild plants and followed the migrations of animals. our lives were lived in small bands. everything was shared. no one had more power or wealth then anyone else. 10,000 years ago, people began to farm and live in permanent settlements. soon, villages, towns and cities evolved and life changed. thousands lived within city walls. we specialized in a single task, and depended on others for everything else we needed.

in time, we became divided into rich and poor, as our human relationships became ever more complex. archaeologist william sanders. i think all human societies are the product of a process of cultural evolution. in general, this evolution leads to an increase in the size of societies, an increase in the complexity of their interaction and institutions. it also leads to more economic interdependence among households within a society, and among societies. keach: to trace the evolution of human societies in the new world, an archaeological team comes here to mexico's tehuacan valley. the team is led by veteran archaeologist scotty macneish. they are seeking evidence of the first inhabitants of the valley. when macneish first excavated here in 1962,

he discovered a time capsule of human occupation at a site called purron cave. macneish: here we are back at purron cave. we really haven't dug in it in almost 30 years. walls all preserved. even the trowel marks we made to mark off strata are still preserved and we have all sorts of neat floors of charcoal one on top of the other. the amazing thing about this cave is that we really have unbelievable preservation. the reason we have preservation is it's so dry in this area that the bacteria of decay that destroy things can't live, so anything that's dropped in here, it dries up and dehydrates and lasts forever. keach: as macneish dug deep into the cave, traces of an early people emerged from an archaeological stratum he called el riego.

macneish: here is our el riego layer, 8,600 years old. now, in it we not only have a date in terms of the year, but we have some idea of what part of the year. here are grass seeds that flower and meet fruition, which they brought in here sometime in july and august. we have fruits of cosiwica that reach fruition october, november. here is a chupendia; there's one right in front of the cave that's fruiting right now in mid-november. so, from these plants coming out of this layer, plus the artifactual evidence, it looks very likely that this layer was occupied somewhere between july and november. keach: in november, the dry season begins. the landscape around purron becomes a searing desert.

there is no water. even cactus are barren of fruit. during the dry season, the ancient residents must have abandoned purron cave to seek water, plants to gather, and animals to hunt. macneish believes they came here, to another cave that overlooked an oasis, constantly watered by underground springs. mexican archaeologist angel garcia cook, excavated the cave with macneish. cook is now director of the mexican institute of archaeology. yeah, que bueno, yes, el tipo flaco. flaco. keach: this projectile point indicates that this cave was occupied at the same time as purron cave, about 5000 b.c. clues to the diet of the cave's ancient residents

also began turning up. interpreter: this is a piece of maguey that was cooked over a fire and then chewed. it was a species of cactus that they chewed and then spat out. sometimes you can see the mark of people's teeth on these quids. so maguey was clearly a part of the diet of the people that came here at a certain season of the year. this is a leaf of nopal cactus, which you can find during all the seasons, but there are times when people eat it more often because there is nothing else to eat. keach: nopal still grows just outside the cave. macneish's workmen remember droughts when they ate nopal to stave off hunger and thirst.

they call the cactus "starvation food." so, discovering cactus in the cave tells the archaeologists it was occupied during the dry season when both food and water were scarce. pretty good, not bad. needs a little sauce. the most precise evidence that this was a dry-season camp is a tiny, hollow bone. interpreter: this is the bone of a bird, perhaps a duck, which migrates to this region each year only in the winter during the dry season. all this is evidence of the food that they had in this cave and indicates that it was occupied in the dry season in autumn and winter. keach: until recently, another living culture was still following a nomadic way of life.

these are the kung bushmen of south africa. they provide some clues as to what daily life might have been like in the ancient tehuacan valley. [ thunder ] in the rainy season, the desert blooms. the men hunt and the women gather nuts and berries. the kung call this the season of full stomachs and celebrate with dance and song. [ singing ] but during the dry season the kung must camp near a few permanent waterholes. every drop of moisture is precious. in the searing heat, they gather deeply buried roots. the kung survived here by blending their lives

with the seasonal availability of the animals they hunt and the plants they gather. it is an ancient way of life. archaeologist william sanders. >> if you look at human history over the past two million years you can think of it in terms of two major revolutions one going back where man first started using tools and then from then on all the work that was performed was primarily human labor. and then the industrial revolution in the 18th century when you start harnessing all other kinds of energy. during that long block of time from a couple of million years ago until the industrial revolution, there was a point about 10,000 years ago when human beings began to farm, began to practice agriculture, and that harnessed a lot more energy than was possible by just hunting and gathering wild resources. keach: in the old world, we know that agriculture sparked the development of the world's first cities in places like sumer in ancient mesopotamia.

but how did farming begin in the new world ? when scotty macneish first came to the tehuacan valley in 1962, he was seeking the answer to one simple question -- did agriculture evolve here or was it introduced from the old world ? then we'll measure out from the corners. keach: in a stratum of the purron cave that had been laid down thousands of years later than those in which he found the hunters and gatherers, macneish made a discovery that exceeded all expectations. macneish: this is a corn cob, and it's a real little one. keach: it may have looked insignificant, but the shriveled ear dated to about 5000 b.c. it was the earliest evidence of farming ever discovered in the new world. since corn is a staple crop, it would have allowed a nomadic hunting/gathering way of life to evolve into a settled agricultural one.

corn slowly evolved in the new world from tiny ears, like the one macneish discovered, to the size we know today. like staple crops of the old world, such as wheat and barley, corn has a wonderful property. corn can be dried and stored, to provide food year round. corn can also be produced in abundance, so populations grew. step by step, a new way of life took hold. permanent settlements evolved. simple shelters became substantial dwellings to protect young and old alike. macneish returns to the valley where he found the first corn. he is now seeking evidence of the earliest permanent settlement,

perhaps the beginnings of a village. a few miles from the caves, in the ajalpan clay pits, macneish spots a familiar pattern. high in this wall, is a blackened layer of charcoal and just above it, the cobblestone floor of an ancient house. the floor dates to 3000 b.c., 2,000 years later than the hunter-gatherer settlements in the caves. what we're getting here is a big piece of burned clay. it's lying on top of the floor and is, from looking in here, is a piece of the wall. what they did is they took clay and, like the hebrews in ancient egypt, put grass in the clay and then plastered it on the sticks which were the wall of the house. it's very much the same system the indians up in the country have today. we'll get the shape of the house from the post holes,

so, we'll know a lot about this very simple first kind of housing in a permanent village. keach: the cobblestone floors macneish discovered would have been the foundations for small mud and thatch houses, like these. a settlement like this marks a dramatic turning point when early farmers begin to abandon their nomadic way of life for a settled one. so, ajalpan, in fact, is what mao zedong would call the first great leap forward from when people were food collectors to when people were food producers. and once you're food producers, why the sky's the limit in terms of moving on to civilization. but this step has to happen before you can go on. keach: with the advent of agriculture different societies all over mesoamerica began to evolve cultures of enormous complexity. on the western border of what is now honduras lies the ancient maya city of copan.

these are the same ruins described with wonder by stephens and catherwood in the 19th century. today, an international team of archaeologists has converged at copan to mount a massive scientific expedition. the objective is to discover what happens to a society when agriculture gives it the ability to become larger and more complex than ever before. and according to her map, that is where she found that one tomb where we got that really good skeleton. william sanders and colleague david webster are about to excavate a sprawling set of ruins that has lain abandoned and covered by weeds and brush for more than 1,000 years.

beneath what appears to be a natural hill, these archaeologists believe may lie the ruins of an ancient building. slowly, almost imperceptibly, the first clues begin to emerge. these strange figures are portraits of spirits that once adorned a magnificent carved bench, a throne upon which a maya lord sat in council and judgment. huge blocks. yeah. "mega-rocks." remember evelyn, the tomb she found on the other building was right along the front of the terrace starting outside of it, then going underneath it. keach: the buildings begin to give up their secrets. here, the archaeologists believe, lived a noble family. maya royalty often buried their ancestors in a place of honor just in front of their dwellings. a burial is just now being uncovered.

it may contain definitive clues to the status of the people who once lived here. deciphering the clues requires the special expertise of forensic archaeology. clean the rest of the dirt out. okay, that's good. that's what it is all right, a femur. hey, you're lucky. keach: near the elite buildings at copan archaeologists have now discovered many burials. anything else ? they are the special province of physical anthropologist rebecca storey. i have here some skeletons from an elite compound in copan. one of the things we like to be able to tell is gender because being able to tell males from females is useful in reconstructing social organization. our best evidence on the skeleton actually comes from the pelvis which has to be wider in females because of the needs of childbirth. one easy way we can tell sex

is to use the sciatic notch right here and to use what we call our rule of thumb. stick your thumb in. if it moves, it's a female. if you put your thumb in and it doesn't move, it's a male. normally i would expect to find equal numbers of males and females. however, in this case i found twice the number of females to males. and in one patio there were 15 females and only 2 males. the best explanation for this disparity is probably that the males of the household had more than one wife. having multiple wives is common among elite maya and wives would be seen as a form of wealth. this is additional evidence that that was an elite compound. keach: over the last 10 years, excavations have revealed a series of elite compounds, each one a complex of temples, workshops, and residences. like old-world palaces, archaeologists believe that these were the dwellings of maya lords and their retainers.

archaeologist david webster. this person would have been the head of one of the major political subdivisions of the copan political system. he would have been a noble just below the rank of king. he has his own sculptured facades on his buildings. he has a sculptured bench. he's got his own titles. he's able to enjoy altars and status symbols of all kinds in his compound here. he was probably polygynous, probably had a number of wives and concubines. so, he was a very important person indeed and there were probably a number of people like him in this political system who dominated other courtyards with similar political followings. keach: maya society is no longer egalitarian as were the hunter-gatherers. now there are people with more wealth and power than others. one of the consequences of cultural evolution is the creation of social classes. but these nobles did not represent

the highest social level in copan society. less than a mile away from the compound lived the kingdom's royal family. this is the acropolis, a magnificent group of palaces, temples, and plazas. 16 kings ruled here for almost 400 years. after his inauguration, each new king would build his own palace atop those of his ancestors. deep inside the acropolis these earlier buildings have now been discovered. here, a team of archaeologists has tunneled its way to an ancient tomb. so, you got it dug away, you think ? yeah. all right, well, let's do it.

it's pretty complete. a little bit of it stayed behind there, but not too bad. boy, it's a big piece of jade. feels like it's got an indentation on the bottom. it's probably an ear flare. along with the burial was a hoard of precious jade. in tombs like these, maya kings were often buried with special offerings to accompany them on their voyage to the world of the dead. archaeologist william fash. jades can tell us specifically about what he was wearing the day he went to the other world. this one in particular is a nice example of a human figure. these four jades with human figures were the central pieces of the jade collar that he wore when he was placed on the slabs in the center of the tomb. there are also pieces that represent ear flares or ear rings actually that the individual wore. the men wore earrings in maya society, too.

and the way this worked was that this flowery part went on the outside and the spool and the counterweight came in through the back and this held them in place. and also it allowed a little bit of balance. if you just had the heavy jade on the front, the guy would have been falling over. this is very elaborate jewelry and is also an indication of the status and wealth of this person because jade itself is harder than steel, yet the maya had no metal tools. so each one of these represents literally hundreds if not thousands of man-hours of patiently carving away at this basically with just sand and water. so, this is quite an assemblage of wealth in a single spot and he went into the other world very well dressed for the occasion. keach: as cultures evolve in complexity, finer distinctions are made about social status. jewelry fashioned from jade, rainbow-hued headdresses crafted from the feathers

of rare tropical birds, and the pelts of jaguars could only be worn by maya lords. kings paid special attention to the symbols of their rank. like the pharaohs of ancient egypt, they expressed their power in monumental buildings -- palaces and temples erected in their honor. archaeologists in the acropolis group are just now uncovering buildings commissioned by the earliest kings of copan. their problem is to figure out who built what. it's not very far below the ground, is it ? yeah, we cleaned a lot of it out. keach: this building has recently been uncovered beneath one of the great plazas. etched across the risers of this ancient stairway is an inscription, but the archaeologists are not yet sure of what it says. i'm just not quite sure what's going on. this could be... modern archaeology often requires the coordinated insight

of a number of specialists. this right here is a king. right. this is a face. that's the face there. there's the eye. there's the nose. keach: linda schele is an epigrapher, a specialist in deciphering ancient hieroglyphs. the evolution of maya society included the development of an elaborate writing system that is just now being understood. fash: you need to have people who are really familiar with this stuff, who can look at maya symbols and say, "well this means corn. "this means tree. this means sun. "this means venus, moon..." whatever it may be. and you also need people who can look at the writing system. so you're combining different points of view as well as different sets of information. and this is eh, bu, eb. so that's the name of the stairs ? it's the name of the stairs. "the precious steps." schele: archaeology studies what people left in the ound, the debris of their lives.

an epigrapher and an iconographer studies the messages that people in power wish to give to their people, how they understand and view the world. this is the most likely one to be his name. and i'd say there's probably a 60%, 70% chance it's going to come out to be butz chan. keach: butz chan was the 11th king in copan's royal dynasty. a king who could organize the construction of great buildings obviously had wealth far beyond anyone else in the city. but where did that wealth come from ? the copan valley, several miles wide, is watered by the copan river. today the fertile bottom lands near the ancient palaces of the elite lords are owned by a few wealthy families. on the hillsides, peasants try to eek out a living

on inferior land. the archaeologists speculate that this same pattern would have existed in ancient times. by surveying the hillsides, they have discovered the homes of the ancient maya commoners. 3 meters and 80 centimeters. let's get it on the map. by mapping each house site, they create a picture of maya settlement. over two-thirds of the population, mostly commoners, lived in the hills far from the acropolis on the compounds of the elite who controlled the best lands. to confirm that the ancient residents of the hillsides were farmers, archaeologists employ new scientific tools. using samples of mud from a hillside swamp, a picture can be taken of agriculture thousands of year ago. each of these microscopic flecks of pollen contains clues to their identity --

a characteristic shape for each variety of plant. the pollen reveals clear evidence of cornfields. so a majority of the ancient maya, like these farmers today, tilled the soil to support the wealthy few. control of the most fertile bottom lands brought great power to the lords. here on the acropolis, that power was expressed in grand temples and palaces, a carefully constructed stage for royal display. in the maya, we see a pattern of cultural evolution found throughout the world. in the old world, all the great civilizations resulted from efficient forms of agriculture and the monopolization of that wealth by a few. as archaeologists delve ever more deeply into our shared human history,

they are discovering that complex civilizations independently arose in similar ways throughout the world. the advent of agriculture propelled many new world societies to greater heights of culture. 300 miles to the west of copan, in mexico, the kingdom of the zapotecs emerged at about the same time as the maya. on a towering hilltop, monte alban became the capital of an opulent civilization of kings and nobles, writing and art. this was the home of the zapotecs, a separate ethnic and cultural society, contemporary with but distinct from the maya. monte alban grew to be much larger than copan. 30,000 people lived in the city center,

supported by 100,000 more in the surrounding valley. there is general agreement about the size of monte alban, but how the city managed to become so large and important is still shrouded in mystery. archaeologist elsa redmond thinks this strange gallery of grotesque carvings may hold the key to that mystery. redmond: these figures have been subjected to all kinds of interpretations -- dancers, swimmers, ecstatic priests, medical anomalies. but there's certain clues on these stone slabs that help us understand what they represent. they are nude male figures.

their eyes are closed. their mouths are open, or grimacing, in pain. their arms are braced and with with cupped hands in submissive gestures. their legs are splayed out in awkward, distorted poses. this one is wearing a hair knot and pony tail that we know warriors wore in mesoamerica. also an ear spool, that suggests he might have been an individual of high status. it's important that he's shown naked because in mesoamerica captives were shown naked as a sign of their humiliation. keach: redmond thinks that each of these figures may represent a chief or warrior from a competing group who had been captured and taken to monte alban to be sacrificed.

redmond: the fact that there are 300 or more of these male figures portrayed on this building is important because it suggests that the earliest rulers of monte alban claimed this hilltop in the context of endemic warfare in the valley. keach: archaeologists call warfare a "cultural universal," a feature of almost all human societies. in this mural, maya lords capture a victim during a raid. in copan, the captive would have been taken to a temple in the west court and sacrificed to the maya gods of the underworld. linda schele believes the ritual involved hundreds of people in a public ceremony of sacrifice and dance. the image of the dance has people dressed in the most incredibly elaborate costumes.

it's almost like if you've ever seen the mummers dance in the thanksgiving day parade with the great feather fans around them. it was just like that. only these were iridescent, green quetzal feathers. there would have been musicians. they would have played drums this high... turtle shells with deer horns. they had great rattles like this. they had long wooden trumpets. they had whistles of all sorts, so that the whole place would have been filled with this incredible cacophony of sound. at the right moment, the king would pull a stingray spine through his tongue or cut through his genitals and pull paper or pull rope through it to draw the blood. some of the captives would have been sacrificed up above and thrown down to this part of the ceremonies.

others of them the king himself would dispatch, and then tie them up in a ball. and that's when the captive go as the sacrificial messengers into the other world to make sure that the ancestors and the gods lend their power to this place. keach: as gruesome as it may seem, warfare is often a ritual activity among early civilizations. but as societies became larger and more complex, the goal of warfare shifted from ritual to political conquest. evidence for this shift appears clearly at monte alban. about 500 years after these carvings of ritual victims were made, monte alban had grown dramatically. more than 20 new buildings were constructed in the main plaza. the royal palace was enlarged from a narrow structure to an expansive compound. much of this growth was made possible

by a new kind of warfare, which is described by hieroglyphs found on this building, among the earliest writing to appear in mesoamerica. archaeologist elsa redmond. >> each of the 50 or so carved stone slabs on this building has the following elements -- first an upside-down human head in profile with lifeless eyes. some have face painting. in mesoamerica, an upside-down head like this refers to conquest. above that is a constant element. this is a hill glyph, which in several mesoamerican writing systems means hill or place. and above it is an element that varies on each of the 50 stone slabs. in this case, it looks to us like a crown, that refers to the specific place that was conquered by monte alban. the three elements put together -- the upside-down human head means conquest,

the hill means place, the element on top means particular place -- refers, then, to 50 or so places that were conquered by monte alban. keach: by a.d. 700, monte alban had greatly expanded its domain through conquest. the zapotec kingdom now included the entire valley of oaxaca. as a result, they created a city and state with a population approaching 200,000 people. throughout the world, conquest of territory fueled the evolution of ever more complex societies. nowhere was this more apparent than in ancient rome. by a.d. 200, the roman dominion had expanded through force of arms to include almost the entire mediterranean and most of the known world.

the result was a vast influx of tribute to rome -- money, goods and slaves to propel the development of one of the most complex societies in the ancient world. but warfare is not the only way that human societies expand. in the tehuacan valley, archaeologists have made a startling discovery. near where scotty macneish excavated the caves, a river that flows only in the wet season has cut through what appears to be a natural hill. in the cut, archaeologists have discerned walls of large rocks, evidence that the hill was actually man-made, an ancient dam of massive proportions. the extent of the dam and the reservoir it created can be seen from a nearby hillside. archaeologist charles spencer. this sea of mesquite and cactus that you see below here

was once the reservoir impounded by the dam that stretched nearly half a kilometer from that cliff face on that side all the way over to this cliff face over here. at its peak, the reservoir surface area equaled 40 football fields. keach: spencer has determined the reservoir's size by measuring the silt that had built up behind the dam. we're behind the dam now, walking through a channel cut right into the silts that were deposited behind the structure. these silts that you see on both sides were brought in here by the water that flowed into the reservoir. when the water hit the dam and stopped, the silts were dropped and deposited in a series of layers. keach: the silts show just how deep the dam once was. the top of this mountain of sediment

would have been the floor of the reservoir. spencer: it dawned on me after a few days that what i was dealing with here was an engineering feat, the magnitude of which was hard to grasp at the beginning. the planning, the foresight, the organization that was required to carry out this incredibly massive task was something that i could only appreciate after days of intensive study. keach: archaeologists think the dam was built to store water to irrigate agricultural fields. in the nearby town of cuicatlan, a living example for the effects of irrigation can be seen. cuicatlan is located in the tehuacan valley, an arid region of mexico with insufficient rainfall for successful agriculture. but the town has abundant water, thanks to a nearby river.

harnessing this forceful river is the matamba dam. the dam diverts water into a central canal, which winds down the mountain side on a journey 15 miles long. along the way, a canelero, or a canal keeper, opens a sluice gate to send water into a network of smaller feeder canals. below, a farmer waits to irrigate his cornfields. farmer: el agua es la vida porque... interpreter: water is life. because without water we cannot farm. that's why we say water is life. having water, we're happy. we can sow any plant we want -- the beans, the tomatoes, the chile, melon --

all because of water. keach: the irrigation system at cuicatlan has increased food production dramatically, but it has also brought with it a need for administration. anthropologist bob hunt is an expert on how irrigation affects the way we organize our societies. hunt: in order to operate an irrigation system now, not just the dam itself, but the irrigation systems downstream, where you're taking water from the river and moving it a considerable distance and putting it on fields, on the fields of many people -- that's not an easy task to accomplish. and to accomplish it without conflict and to keep everybody more or less satisfied requires a considerable degree of organization. keach: in ancient times, powerful nobles who controlled the state probably managed the irrigation system. today in cuicatlan, the farmers themselves exercise that control through their cooperative called the unidad. each night, farmers request their daily allotment of water

from unidad officials. interpreter: when can i have water ? you have to wait. you can have it saturday. tomorrow's friday. tomorrow i'm full. keach: the unidad makes sure that each farmer receives his fair share. they also organize the maintenance of the system. the central canal requires the organized labor of many people. the president of th unidad oversees the annual cleaning. each farmer is required to help maintain the canal or lose his allotment of water. so, in cuicatlan, the distribution of water has created the need for managers, and with managers comes a potential for coercive power. in an arid region of the old world,

the pharaohs organized labor to control the floodwaters of the nile... producing plentiful crops. over the centuries, such control not only increased the wealth and power of lords and pharaohs, but also sent the kingdom of egypt on a path toward increased social and political complexity. now archaeologists are discovering a similar pattern near the pyramids of the valley of mexico. this is teotihuacan. more than 125,000 people once lived here. the city is 20 times the size of ancient copan. it is more than 4 times as large as monte alban. here was a society of lords and priests,

intricate art and architecture. the pyramids of the sun and the moon are among the largest buildings ever constructed in the ancient new world. by a.d. 600, this was the most complex society in all of mesoamerica. archaeologist william sanders. in this area where i'm standing, which is right on the southern edge of the ancient city, there are between 80 and 100 permanent springs. there is some convincing evidence that at the time of the peak of the ancient city, the water from these springs was harnessed into an elaborate canal system that provided permanent irrigation for at least 7,000 or 8,000 acres of land down on the bottom of the teotihuacan valley, rich, fertile alluvium with very high productivity. this must have provided at least one of the major sources of the production of staple foods for the ancient city at its peak.

keach: some archaeologists think the irrigation system was controlled by the state -- the king and his high-ranking elite -- just as the unidad controls it in cuicatlan today. that control gave the elite enormous power, which can be seen in these massive buildings. man: this is the political center of teotihuacan. the temple of quetzalcoatl behind us represents the power of the state. the sheer volume of teotihuacan -- of the temples, the hundreds of temples along the street of the dead, the massiveness of the pyramid of the sun, the pyramid of the moon, the temple of quetzalcoatl with its dedicatory burials -- attests to the ability of the state to collect taxes in the form of labor, as well as goods and skills needed to put together and control a city of this size. keach: teotihuacan must have had an extensive bureaucracy.

everywhere there is evidence of state management, of control. the layout of the city itself was planned. religious and government buildings line two main avenues, with house compounds arranged behind, in a grid pattern. warren barbour has studied these compounds since 1962. this is the central patio of the apartment compound, called sequala, which is a typical apartment compound at teotihuacan. it's about half a football field on the side. it contains a central patio, a temple on the east side, and four apartments. to get the picture of this, you have to see elaborate paintings on the lower sections of the walls... the upper walls painted like wallpaper in reds and whites and greens. the pillars would go up to roofs with wood and covered porticoes,

where children would be sitting and playing a game like parchesi. you would see dogs walking around, food being cooked, baskets in corners, stacks of grain. this would have been the center of life in the compound. and you have to remember that this would be repeated 2,000 times in other apartment compounds throughout teotihuacan. keach: in many ways, teotihuacan was a dramatic step forward in the evolution of ever more complex societies. it was the beginning of a cosmopolitan, urban way of life. the city's fame became a magnet, drawing immigrants from throughout mesoamerica. excavations in one of the compounds is now revealing that the people who once lived here were traders and merchants from other cities. michael spence is directing the excavation. he has just found some pottery in one of the ruins.

spence: it's painted here. you can see that there's red paint over most of the interior except up along the rim. there's a little bit up there, too. it's going to be very delicate, very fragile. and i'll try and reassemble it and see if there's any sort of a design on it, or if it's just a solid red. we've been picking up pottery from all over the fields. and in examining the pottery, we saw that a high proportion of it was foreign to the city. and we knew from the work of others that it came from the oaxacan area. it turns out that actually it was produced here. the people moved here, but they continued to make pottery in their home tradition. keach: the pottery indicates that this compound may have been occupied by traders from far-off monte alban, an indication of a complex economy here. bill sanders. one of the aspects of culture that is extraordinarily variable is the economy. economy means the ownership of property

and the production and distribution of goods. there are cultures and economies in which every nuclear family is self-sufficient. and then there are economies where there is considerable interdependence among the various households. one of the measures of economic complexity is just the amount of what we call division of labor -- occupational specialization. keach: archaeologists have recently discovered evidence of occupational specialization in teotihuacan, like the manufacture of clay figurines. figurines came in a variety of styles, many painted and highly detailed. thousands of these sculpted faces have been discovered. they were probably used in ritual. many are exactly the same, indicating they were mass produced in molds. across the atlantic is fez, morocco, a city that has changed little in a thousand years.

here can be found an analogy for the economy of ancient teotihuacan. this is a leather tanning workshop, where fine skins are produced for market. the tanning requires the labor of literally dozens of specialists -- to remove the hair, wash the hides, tan them, and get them ready for market. such economic specialization is only possible in a city, a place where a dense population of consumers provides a demand for the goods massroduced in these workshops. the emergence of cities is a common thread in the worldwide tapestry of human history.

as cities grew, the pace of commerce and innovation quickened. the gulf between rich and poor widened and political power was gathered into the hands of a few. today most of us are city dwellers. we take for granted our rich and complex way of life. as archaeologists reach back in time, they reveal the individual steps in the long human journey that led us here. it is an odyssey that follows similar and predictable patterns in the old world and the new.

bands of nomadic foragers gave way to settled villages once a staple crop developed. a more efficient agriculture freed some of us from the burden of farming to create wondrous works of art. wars and conquest sparked the rise of great cities. everywhere and at every opportunity, human societies in the old world and the new engaged their environments to organize their lives with inventiveness and creativity. slowly, out of the past, the pattern of human history comes into focus. captions by captionamerica, pittsburgh, pa.

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